A street camera is almost never watched live. It is mostly used afterwards, provided someone asks for the footage in time.
How a city network works
A town's cameras are linked by fibre or radio to a control room: a room, a wall of screens, a few operators. French law calls cameras on public streets vidéoprotection, and those in private places vidéosurveillance.
An operator can only really follow a few screens at once. In a city with hundreds of cameras, the vast majority of footage is seen by no one. It is recorded, then erased.
Three uses dominate:
- Live: following a demonstration, a match, an incident reported by radio.
- Afterwards: police or courts request footage of a precise place and time. This is by far the main use.
- Plate reading (ANPR): dedicated cameras read number plates and compare them to lists of wanted vehicles.
How a camera works technically is covered in Security cameras.
What the law says in France
- Every camera on a public street needs authorisation from the prefect, after the opinion of a local commission.
- It must not film inside homes, nor their entrances in detail.
- Signs must mark the filmed area and say whom to contact.
- Footage is kept 30 days at most, often less. Then it is erased, unless an investigation has requested it.
- Anyone can ask to see footage in which they appear, from the person named on the sign. Refusal is possible for security or investigation reasons; it can be challenged before the local commission.
Other countries have their own rules; in the UK, for instance, requests go through a subject access request under data protection law.
Live facial recognition in the street is not allowed in France. At European level, the 2024 AI regulation forbids it to law enforcement, except for narrow cases (searching for a victim, an imminent terrorist threat) supervised by a judge.
Automated video analysis, without face recognition, was trialled for the 2024 Olympics: spotting an abandoned object, a crowd surge, a person on the ground. Its future is the subject of debates and successive laws: check the law as it stands when you read this.
Does it work?
The most solid answer comes from an analysis of 76 studies carried out over forty years (Piza and colleagues, 2019):
- a modest drop in crime where the cameras are, around 13% on average;
- a clear effect on car parks and vehicle-related theft;
- no measurable effect on violence: nobody thinks about the camera in the middle of a fight.
In France, the Court of Audit noted in 2020 that no overall link had been established between how many cameras a city has and its crime level. A study commissioned by the gendarmerie in 2021 found that footage had contributed to only a small fraction of solved investigations.
What cameras do well: retrace a route afterwards, confirm a time, find a vehicle. What they do badly: prevent.
What's actually useful to you
You are a victim or a witness. Report it within days, giving the exact place and time. The complaint is what lets the police request the footage before it is erased. After a month, it no longer exists. Note the shops nearby too: their private cameras often have a better view than the city's.
You want to know where the cameras are. Signs, town council minutes (installation is voted and funded in public), some cities' open data, and collaborative maps like OpenStreetMap, where volunteers log cameras.
You want to see your footage. Write to the person named on the sign, within the retention period, giving place, date, time and a description of yourself.
You care about your privacy. A street camera is one link among many; your phone, your payments and your badges say far more. See Se retirer du système.
During a long blackout. A camera network depends on power and links. Without them, it goes dark like everything else, see Les réseaux, de la source à la prise.